Isolation head and method of use for oilfield operations

Abstract

A method and apparatus according to which at least part of a wellhead is fluidically isolated from excessive pressures, temperatures, and/or flow rates during a wellbore operation using an isolation head, the isolation head including an isolation spool and an isolation sleeve.

What is claimed is: 
     
         1 . An apparatus, comprising:
 an isolation spool adapted to be operably coupled to a wellhead; and   an isolation sleeve operably coupled to the isolation spool and moveable relative thereto;   wherein, when the isolation spool is operably coupled to the wellhead, the isolation sleeve is adapted to move, relative to the isolation spool, to sealingly engage first and second packoff surfaces; and   wherein, when the isolation sleeve is sealingly engaged with the first and second packoff surfaces, the isolation sleeve is adapted to isolate at least a portion of the wellhead from a fluid flowing through the apparatus.   
     
     
         2 . The apparatus of  claim 1 , further comprising:
 an actuator operably coupling the isolation sleeve to the isolation spool and adapted to move the isolation sleeve relative to the isolation spool.   
     
     
         3 . The apparatus of  claim 2 , wherein the actuator comprises:
 a rack gear operably associated with the isolation sleeve; and   a pinion gear engageable with the rack gear to move the isolation sleeve.   
     
     
         4 . The apparatus of  claim 1 ,
 wherein the isolation spool defines an internal passage; and   wherein the isolation sleeve extends within the internal passage of the isolation spool.   
     
     
         5 . The apparatus of  claim 1 , further comprising:
 an isolation valve connected to the isolation spool;   wherein the isolation valve is positioned between the first and second packoff surfaces when the isolation spool is operably coupled to the wellhead; and   wherein the at least a portion of the wellhead comprises the isolation valve so that, when the isolation spool is operably coupled to the wellhead and the isolation sleeve is sealingly engaged with the first and second packoff surfaces, the isolation sleeve is adapted to isolate the isolation valve from the fluid flowing through the apparatus.   
     
     
         6 . The apparatus of  claim 5 , further comprising a fluid line adapted to:
 bypass the isolation valve, and   place the wellhead and the apparatus in fluid communication so that first and second fluid pressures acting axially on opposing end portions, respectively, of the isolation sleeve are equalized with a third fluid pressure in the wellhead.   
     
     
         7 . The apparatus of  claim 1 , further comprising one or more valves connected to the isolation spool and adapted to isolate, from atmosphere, first and second fluid pressures acting axially on opposing end portions, respectively, of the isolation sleeve. 
     
     
         8 . The apparatus of  claim 7 , further comprising a fluid line adapted to place the wellhead and the apparatus in fluid communication so that the first and second fluid pressures acting axially on the opposing end portions, respectively, of the isolation sleeve are equalized with a third fluid pressure in the wellhead. 
     
     
         9 . The apparatus of  claim 7 , further comprising an isolation valve connected to the isolation spool so that:
 the isolation spool is positioned between the isolation valve and the one or more valves; and   the isolation valve is positioned between the first and second packoff surfaces when the isolation spool is operably coupled to the wellhead;   wherein the at least a portion of the wellhead comprises the isolation valve so that, when the isolation spool is operably coupled to the wellhead and the isolation sleeve is sealingly engaged with the first and second packoff surfaces, the isolation sleeve is adapted to isolate the isolation valve from the fluid flowing through the apparatus.   
     
     
         10 . The apparatus of  claim 9 , further comprising a fluid line adapted to:
 bypass the isolation valve, and   place the wellhead and the apparatus in fluid communication so that the first and second fluid pressures acting axially on the opposing end portions, respectively, of the isolation sleeve are equalized with a third fluid pressure in the wellhead.   
     
     
         11 . The apparatus of  claim 1 , further comprising the first and second packoff surfaces. 
     
     
         12 . The apparatus of  claim 1 , further comprising the first packoff surface. 
     
     
         13 . The apparatus of  claim 1 , further comprising the second packoff surface. 
     
     
         14 . The apparatus of  claim 1 , further comprising the wellhead. 
     
     
         15 . The apparatus of  claim 1 , further comprising a frac tree, the frac tree comprising one or more valves connected to the isolation spool and adapted to isolate, from atmosphere, first and second fluid pressures acting axially on opposing end portions, respectively, of the isolation sleeve. 
     
     
         16 . A method, comprising:
 isolating, from atmosphere, first and second fluid pressures acting axially on opposing end portions, respectively, of an isolation sleeve;   equalizing the first and second fluid pressures acting axially on the opposing end portions, respectively, of the isolation sleeve with a third fluid pressure in a wellhead, the wellhead comprising an isolation valve;   after equalizing the first and second fluid pressures with the third fluid pressure, opening the isolation valve of the wellhead; and   after opening the isolation valve of the wellhead, sealingly engaging the isolation sleeve with first and second packoff surfaces, wherein the isolation valve of the wellhead is positioned between the first and second packoff surfaces.   
     
     
         17 . The method of  claim 16 , further comprising:
 isolating, using the isolation sleeve, the isolation valve from fluid flowing through the wellhead.   
     
     
         18 . The method of  claim 16 , wherein sealingly engaging the isolation sleeve with the first and second packoff surfaces comprises:
 moving the isolation sleeve, relative to the isolation valve, so that the isolation sleeve extends through the isolation valve.   
     
     
         19 . The method of  claim 18 , wherein the equalization of the first and second fluid pressures with the third fluid pressure facilitates the movement of the isolation sleeve. 
     
     
         20 . The method of  claim 16 , wherein equalizing the first and second fluid pressures with the third fluid pressure comprises connecting a fluid line to the wellhead;
 wherein the fluid line bypasses the isolation valve of the wellhead; and   wherein the first and second fluid pressures are equalized with the third fluid pressure via the fluid line.